ZURICH, Sept 24 (Reuters) - Swiss drugmaker Roche upped its bet on personalised cancer treatment on Monday, saying it is now ready to sell a blood test around the world that can identify common gene mutations from solid tumours from a patient's blood.

The blood test, called FoundationOne Liquid, is among initial products to emerge from Foundation Medicine after Roche spent $2.4 billion on the U.S.-based genetic profiling company this year on the conviction that future cancer treatment will be tailored to individual characteristics of a patient's tumour.

Foundation's new blood test can identify circulating tumour DNA as 70 of the most commonly mutated genes in solid tumours, Roche said, including features which may help identify patients most likely to benefit from cancer immunotherapy.

While Roche is the biggest cancer drug maker, it has lost ground to rivals like Merck in early rounds of cancer immunotherapy. Roche is wagering that Foundation Medicine's tests will be needed by oncologists to guide how they fight tumours that vary by patient, regardless of which firm's drug they choose to use.

"Cancer is a disease of the genome and genomic profiling of every patient's tumour at the start of their treatment journey will provide transformative outcomes for patients," said Sandra Horning, Roche's chief medical officer, in a statement.

Foundation Medicine already sells a cancer test, FoundationOne CDx, to assess cancer-driving genomic alterations in 324 genes -- more than four times those assessed with the new blood tests -- but it requires a tumour biopsy.

Such material is not available from everybody, including in non-small cell lung cancer, where some 15 percent of patients are not eligible for tissue biopsy and about 10 percent have samples too small to evaluate.

With the new test, cancer doctors draw patients' blood and send it to Foundation Medicine's laboratory.

There, gene sequencing determines, among other things, if a tumour's characteristics make it a prime candidate for immunotherapy drugs that stimulate the body's T cells to go on the attack.

While sales of Merck's Keytruda immunotherapy have quickly outstripped Roche's competing product, Tecentriq, in non-small cell lung cancer treatment, Roche is seeking to benefit from its rival's success: The two companies in May signed a pact to cooperate on companion diagnostic tests from Foundation Medicine for Keytruda. (Reporting by John Miller, editing by Silke Koltrowitz)